One of HBO's most compelling documentaries is "Terror in Mumbai" - a gripping minute by minute account of the attack by Pakistani terrorists on a train station and several hotels in Mumbai. The only surviving gunman is featured prominently in film as a result of an interview he gave on a hospital gurney shortly after he was captured..

He has now apparently paid the ultimate price for his dastardly crime.

India secretly hanged the lone survivor of the Pakistan-based militant squad responsible for a rampage through Mumbai that killed 166 people, sparking celebrations days before the fourth anniversary of the assault on the financial capital.

Pakistan national Mohammad Ajmal Kasab was the enduring image of the bloody assault, which traumatized India and raised fears of copycat attacks on foreign cities. Pictures of the boyish gunman wearing a black T-shirt and toting an AK-47 rifle as he strode through Mumbai's train station were published around the world.

Kasab was executed on Wednesday morning amid great secrecy, underscoring the political sensitivity of the November 26, 2008, massacre, which still casts a pall over relations between nuclear-armed rivals Pakistan and India.

"All the police officers and personnel who lost their life in the battle against the terrorists have today been served justice," Home Minister Sushil Kumar Shinde said after Kasab was hanged in a jail in Pune, southeast of Mumbai.

Kasab was charged with 86 offences, including murder and waging war against the Indian state, in a charge-sheet running to more than 11,000 pages.

It was the first time a capital sentence had been carried out in India since 2004. There was celebration on the streets of Mumbai and other cities as news of the execution spread, but militant groups in Pakistan reacted angrily, as did residents of his home village of Faridkot.

People set off fireworks and handed out sweets in Indian cities. Some held up photos of Kasab with a rope noose superimposed over his head.

Attack survivor Vishnu Zende, who was working at Mumbai's train station where nearly 60 people were killed, said the execution brought it all back.

"When I heard the news of Kasab's execution today, I remembered those horrifying moments of the attack," Zende said.

"My eyes were filled with tears."

These terrorists were mostly kids manipulated by a master terrorist in Pakistan. But Kasab knew full well what he was doing and while it won't serve as a lesson to other terrorists, it certainly has brought closure to the families of victims.